A comparison of taste responses from the fungiform, foliate and circumvallate papillae will be studied by simultaneous recording from the chorda tympani and glossopharyngeal nerves. Hypoglossal stimulation will be used to increase the transport rate of the taste stimulus to the taste buds of the circumvallate and foliate papillae by mechanical movement of the tongue. The effectiveness of a variety of bitter stimuli will be measured by response-concentration functions. The hypothesis that "the relative reactivity of taste receptor cells to different chemicals is determined by inherent properties of the tissue from which the cells are formed" will be tested by simultaneous recording of chorda tympani and glossopharyngeal nerve bundles that innervate the foliate papillae. The taste system is excellent for study of the general problem of molecule-cell interactions that are so important in biology and medicine. Since the taste cells are rapidly renewed, the process of cell differentiation can also be studied by examining the importance of nerve contact in taste cell differentiation. Bitterness is of great importance in the development of both rodenticides and medicines.